Auto refresh comments in Wordpress

I want to create a real time comment system on Wordpress. I use the following code:

<script type="text/javascript">
function Ajax(){
var xmlHttp;
	try{	
		xmlHttp=new XMLHttpRequest();// Firefox, Opera 8.0+, Safari
	}catch (e){
		try{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); // Internet Explorer
		}catch (e){
		    try{
				xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
			}catch (e){
				alert("No AJAX!?");
				return false;
			}
		}
	}
	xmlHttp.onreadystatechange=function(){
		document.getElementById('ReloadThis').innerHTML=xmlHttp.responseText;
		setTimeout('Ajax()',2000);
	}
	xmlHttp.open("GET","http://www.gprsmms.com/wp-content/themes/default/comments.php",true);
	xmlHttp.send(null); 
}
window.onload=function(){
	setTimeout('Ajax()',2000);
}
</script>

Code (markup):

http://www.gprsmms.com/wp-content/themes/default/comments.php is the path to comments file and #ReloadThis is the ID of the DIV tag.

The page refreshes after some x seconds.

On the site, it shows: Please do not load this page directly.

How ca I fix this?

Thank you in advance!